The invention concerns a guidance device for a thrust reverser system of a jet engine mounted on a mast comprising at least two guide pieces fastened to the upper frame integral with the mast and pieces to be guided fastened to a moving fairing.
The actuation of the thrust reverser system of certain turbojet engines is effected by the displacement by known means, such as jacks, of a section located in the rear part of the nacelle fairing.
The displacement toward the rear of the section has the effect of:
extending the reverser cascades retracted within the nacelle;
carrying along the closing means of a known type, such as blocker doors, to close off the secondary jet downstream from the reverser cascades;
redirecting in the upstream direction the entire flow of air coming from the fan, through the cascade.
This displacement results in a deployed position of the exhaust reverser system and furnishes a reverse thrust mode, when the section is moved toward the bow, the thrust reverser is in a forward thrust mode, in a stowed position.
The invention concerns more particularly the guidance device mounted between the mobile reverser cascades and a stationary part, such as the upper and lower frames of the nacelle integral with the mast from which the jet engine is suspended.
French Pat. No. 2,184,021 describes a guiding device for a cowling ring capable of varying the cross section of the jet pipe in a jet engine comprising a variable pitch fan. The ring is displaced so as to form an air inlet when the fan operates in reverse. The device contains two guide pieces or rails, parallel to the axis of the nacelle, attached to the mast and to each other by means of crossbraces, wherein the pieces to be guided and fastened to the ring are slidably guided. The pieces have a T-shaped part which engages in the guide rail.
The part of the rail cooperating with the T-shaped parts is covered by a plastic layer which assures tightness and ease of translational movement. Tightness is obtained by the pivoting of the T-shaped part under the weight of the ring, with the opposing edges of the transverse bar forming two lines of sealing contacts.
The functions of guidance and tightness are suitably assured by the above-described device, however, the ease of translation is doubtful, because it is necessary to overcome the contact forces developing along the two sealing lines.
French Pat. No. 2,132,380 eliminates this disadvantage, but at the price of increased complexity. Each half of the fairing carries two sets of inversion blading supported between two spars extending longitudinally. Sliding elements, having a T-shaped part, are attached to the upper spar of the upper blading and to the lower spar of the lower blading and cooperate with the slots provided in the upper and lower frame elements. The spars further carry a groove which cooperates with a wing of an actuating device to retain the bladings and to make possible their sliding. The wings of the actuating device play an important role only at the onset of the motion of the blades. When the blades arrive in their positions, only the elements sliding in the slots provided in the frame elements ensure the guidance and support of the weight of the blades and of the forces generated by the inversion of the gas flow.
In the final phase of the installation of the blades, difficulties similar to those found in the preceding patent, are encountered. Furthermore, no plastic coating is provided in the slots to facilitate displacement.